The lesson of LTCM was that no trading operation is better than its ability to withstand losses. This lesson was proved in spades, in 2008, at highly leveraged banks such as Bear Stearns and Lehman Brothers.
A second lesson is that seemingly unlikely events may be more likely than market history suggests. Russia had not defaulted since 1917, but that didn’t stop it from happening in 1998.
And a further lesson of LTCM’s demise was that the widespread belief that liquidity offers safety is, in fact, an illusion, and a terribly dangerous one at that.